Capt. Troy Posted November 28, 2018 Report Share Posted November 28, 2018 "It is just hard for my little pea brain to accept the fact that that little bitty lip could cause a speed loss of several miler per hour. If I am understanding you correctly............ " It takes very little to create drag on the bottom of the hull. That lip on the grater, Pick ups and transducers all create drag. The big transducer on my Rampage knocked 1 knot off my top end. I still believe the back of the sea chest is where the most drag is coming from along with the protruding screw heads. The faster you go the more drag is created. Just look at what added drag from the gear case does if mounted too low. As for the holes I would be suspect of the straight up and down ones. Seems to me without the angle the water rushing by those straight up and down holes may tend to try and pull water away from the sea chest. As I mentioned before when I lost the grater one time it sucked the water out of my well. Running angle as at speed may be enough to allow the straight holes to catch water enough to supply the well pumps. I never turn my pumps off anytime there is bait in the well running or not. Might forget to turn them back on when I stop. Lots and trial and era I suppose to get the desired results of speed and at the same time not effect the live wells. Messing up my live bait is a deal breaker for me and 62 MPH is fast enough. 1 Quote Link to comment Share on other sites More sharing options...
geeviam Posted November 28, 2018 Author Report Share Posted November 28, 2018 36 minutes ago, Capt. Troy said: "It is just hard for my little pea brain to accept the fact that that little bitty lip could cause a speed loss of several miler per hour. If I am understanding you correctly............ " It takes very little to create drag on the bottom of the hull. That lip on the grater, Pick ups and transducers all create drag. The big transducer on my Rampage knocked 1 knot off my top end. I still believe the back of the sea chest is where the most drag is coming from along with the protruding screw heads. The faster you go the more drag is created. Just look at what added drag from the gear case does if mounted too low. As for the holes I would be suspect of the straight up and down ones. Seems to me without the angle the water rushing by those straight up and down holes may tend to try and pull water away from the sea chest. As I mentioned before when I lost the grater one time it sucked the water out of my well. Running angle as at speed may be enough to allow the straight holes to catch water enough to supply the well pumps. I never turn my pumps off anytime there is bait in the well running or not. Might forget to turn them back on when I stop. Lots and trial and era I suppose to get the desired results of speed and at the same time not effect the live wells. Messing up my live bait is a deal breaker for me and 62 MPH is fast enough. All good points Capt. Troy. In my case, the modification may have added 1 mph or 2 at the most - not sure of either. The 60+ mph club might see better speed gains, because like you said, drag becomes more critical, the faster you go - but I'm not a member of the 60+ mph club, so not sure there either. What thrills me most, is the over-all improvement in the ride and performance of my RF 16, across the board. Quote Link to comment Share on other sites More sharing options...
Capt. Troy Posted November 28, 2018 Report Share Posted November 28, 2018 29 minutes ago, geeviam said: All good points Capt. Troy. In my case, the modification may have added 1 mph or 2 at the most - not sure of either. The 60+ mph club might see better speed gains, because like you said, drag becomes more critical, the faster you go - but I'm not a member of the 60+ mph club, so not sure there either. What thrills me most, is the over-all improvement in the ride and performance of my RF 16, across the board. Copy that. I also look at the Grater as it appears to be stamped Stainless. The stamping leaves a some what flat spot at the back of the hole. I see that as much more drag than a drilled angled hole. It's not a straight path for the water it's more of a dead head for the water to strike. Kinda of like putting a 45 degree fitting in a water pipe. There will be some losses to flow. There are 45 of those little water losses on that plate. Edit to add I can see that plate in a chop seeing some air then water then air and so on. Kinda like havin brakes applied every second on the right side of you car at 50 MPH. 1 Quote Link to comment Share on other sites More sharing options...
geeviam Posted November 28, 2018 Author Report Share Posted November 28, 2018 2 minutes ago, Capt. Troy said: I also look at the Grater as it appears to be stamped Stainless. The stamping leaves a some what flat spot at the back of the hole. I see that as much more drag than a drilled angled hole. It's not a straight path for the water it's more of a dead head for the water to strike. Kinda of like putting a 45 degree fitting in a water pipe. There will be some losses to flow. Excellent observation! Quote Link to comment Share on other sites More sharing options...
Capt. Troy Posted November 28, 2018 Report Share Posted November 28, 2018 I went back and edited my post. To add this. Edit to add, I can see that plate in a chop seeing some air then water then air and so on. Kinda like havin brakes applied every second on the right side of you car at 50 MPH. It may be what your feeling the most in your improvements. 1 Quote Link to comment Share on other sites More sharing options...
mulligan Posted November 28, 2018 Report Share Posted November 28, 2018 58 minutes ago, Capt. Troy said: I also look at the Grater as it appears to be stamped Stainless. The stamping leaves a some what flat spot at the back of the hole. I see that as much more drag than a drilled angled hole. It's not a straight path for the water it's more of a dead head for the water to strike. Kinda of like putting a 45 degree fitting in a water pipe. There will be some losses to flow. There are 45 of those little water losses on that plate. Good point. Maybe that is why some of the "older" hulls of the same boat seem to be faster, they had flat plastic graters. Quote Link to comment Share on other sites More sharing options...
geeviam Posted November 28, 2018 Author Report Share Posted November 28, 2018 (edited) 2 hours ago, Capt. Troy said: I went back and edited my post. To add this. Edit to add, I can see that plate in a chop seeing some air then water then air and so on. Kinda like havin brakes applied every second on the right side of you car at 50 MPH. It may be what your feeling the most in your improvements. I totally agree. Add to it, the RF 16's wide beam compared to its length, and I think those brakes applied on one side are more noticeable. On the other hand, I think the MA 21, with its extra length compared to beam, has an easier time absorbing that torque when "the brakes" are applied on one side. Edited November 28, 2018 by geeviam rephrase Quote Link to comment Share on other sites More sharing options...
mulligan Posted November 28, 2018 Report Share Posted November 28, 2018 Oh, and thanks for all this talk here. You guys are going to make me remove a trailer bunk and spend time crawling under a boat this weekend. 2 Quote Link to comment Share on other sites More sharing options...
JEM Posted November 28, 2018 Report Share Posted November 28, 2018 If it is the lip at the rear of the plate that is causing most of the loss of performance, what do you think of shimming the rear (for example, start with some SS washers for the middle screws , and increase the number of SS washers for the rear screws) so that my factory SS plate ends up flush with the hull, thereby eliminating the lip? I have just the main centerline bait well with one pump, and it works perfectly for my fishing (for example, I have never experienced an air lock), so I am like Capt. Troy somewhat in that I don't want to fix something that ain't broken. Quote Link to comment Share on other sites More sharing options...
geeviam Posted November 29, 2018 Author Report Share Posted November 29, 2018 6 hours ago, JEM said: If it is the lip at the rear of the plate that is causing most of the loss of performance, what do you think of shimming the rear (for example, start with some SS washers for the middle screws , and increase the number of SS washers for the rear screws) so that my factory SS plate ends up flush with the hull, thereby eliminating the lip? I have just the main centerline bait well with one pump, and it works perfectly for my fishing (for example, I have never experienced an air lock), so I am like Capt. Troy somewhat in that I don't want to fix something that ain't broken. What you describe sounds similar to what Hobo did in the past - to modify the SS grater installation to be flush. Might be worth a try! Here is a link to a post that contains his instructions: 1 Quote Link to comment Share on other sites More sharing options...
VsteveV Posted November 29, 2018 Report Share Posted November 29, 2018 7 hours ago, mulligan said: Oh, and thanks for all this talk here. You guys are going to make me remove a trailer bunk and spend time crawling under a boat this weekend. I'm heading in the same direction this weekend! Would it be fair to assume the 18 would have the same benefits? And would you need to remove the bunk to get to the plate? Could you just re position the boat on the trailer just to get that work done? Quote Link to comment Share on other sites More sharing options...
linesider 159 Posted November 29, 2018 Report Share Posted November 29, 2018 I also wouldn't be surprised if the speed gains aren't just from reduced drag, but also reduced turbulence which lowers prop slip. Crazy how a metal cheese grater can spark such a discussion! 2 Quote Link to comment Share on other sites More sharing options...
dabear Posted November 29, 2018 Report Share Posted November 29, 2018 linesider 159 It is almost unheard of to get massive speed gains from a inexpensive bolt on item that can be adjusted or replaced fairly easy so this post has got attention from any speed junky willing to spend a afternoon on his back . Don’t know how many will actually do it but it has a few thinking about it . linesider what was the speed increase that you experienced changing nothing but the cheese grater ? I know that the stainless steel oval shape cheese grater on my HPX is a lot smaller than the RF design . Mine is a 6 “ X 4” oval shape with 22 holes all in a angle to scoop water in holes in front are a little smaller than the ones in the rear . I don’t believe my grater touches the water when the boat is wide open and riding on the pad . The grater on my HPX is level with the hull in the front and the screw holes are recessed and the five mounting screw heads are not sticking up they are level with the plate . 1 Quote Link to comment Share on other sites More sharing options...
VsteveV Posted November 29, 2018 Report Share Posted November 29, 2018 I’m mostly interested in hearing more about the handling and reduction of porpoising. 1-2 mph is nominal and not worth the time imho. Quote Link to comment Share on other sites More sharing options...
Capt. Troy Posted November 29, 2018 Report Share Posted November 29, 2018 I was gonna try this then realized it may effect the ability to back down when I Marlin fish out of the Maverick. In all honesty I really don't believe this item will have that much effect for most. It may effect some hulls more than others and based on what I have seen the grater OEM install is less than consistent from one hull to the next. It's not like they blueprint the bottom of these boats. Then of course there is the chance that the trailer bunks may have bent it slightly or a little more caulk on install raised the plate slightly from the running surface. I'm not gonna get upside down to see unless my bait starts dying. Quote Link to comment Share on other sites More sharing options...
mulligan Posted November 29, 2018 Report Share Posted November 29, 2018 Here is my rough plan to see what you guys think. I really like the idea of the Lexan but not sure if I can find any locally and what I have is to thin. So I will use some Starboard to raise it up some and make it almost flush, as a plus starboard is easy to work with. I will then put a piece of stainless over the starboard for durability. The stainless will be flush with the hull. My only concern is water might get forced between the two but not sure it would or would make any difference if it did. As for holes I will probably have a few more than geevain so I would have water available if I ever run more than one well. I will also put in a hole to relive the pressure in the chest if need be. 1 Quote Link to comment Share on other sites More sharing options...
lurem Posted November 29, 2018 Report Share Posted November 29, 2018 Would it be possible to mount a flush plate with holes over the existing cheese grate and make it flush then secure it? Like an insert? Maybe use the existing cheese grate mounting holes for the screws and just get longer screws? I am like Mulligan and my 4 bunk trailer makes accessing the cheese grate impossible without some maneuvering of my boat and trailer or removing the bunk like discussed above. Quote Link to comment Share on other sites More sharing options...
mulligan Posted November 29, 2018 Report Share Posted November 29, 2018 Anything is possible! If mine was easy to get to I would make an insert to go under the grate and have different grates that attached to the insert depending what I was doing that day. Just using one well, put on a plate with a few holes, fun day and not using the wells slap on a no holes plate and a go fast prop and let her rip! Maybe get Geevian to come down here since he can get to his grate and we can have some fun playing with all this stuff! 1 Quote Link to comment Share on other sites More sharing options...
JEM Posted November 29, 2018 Report Share Posted November 29, 2018 Geeviam, what is the app. size of your plate.....L x W? I ask because I found a 12” x 12”, .375 inch thick for about $40 online. Also, did you use 4200 or 5200? And are your holes all the way through your hull? Did you go with slightly larger diameter screws? Can lexan be worked like wood? For ex, can the corners and edges be sanded? i inntend to look at mine this weekend. I am fortunate because I keep my boat in a marina barn, and can just have the forklift man set it down gently on a wash rack off center to expose the grate. It would make this mod easy peasy for me! I am like you, this would be a very worthwhile mod if it only stopped my mid range porpoising. Any speed gain at all would be just gravy! Quote Link to comment Share on other sites More sharing options...
geeviam Posted November 29, 2018 Author Report Share Posted November 29, 2018 20 minutes ago, JEM said: Geeviam, what is the app. size of your plate.....L x W? I ask because I found a 12” x 12”, .375 inch thick for about $40 online. Also, did you use 4200 or 5200? And are your holes all the way through your hull? Did you go with slightly larger diameter screws? Can lexan be worked like wood? For ex, can the corners and edges be sanded? i inntend to look at mine this weekend. I am fortunate because I keep my boat in a marina barn, and can just have the forklift man set it down gently on a wash rack off center to expose the grate. It would make this mod easy peasy for me! I am like you, this would be a very worthwhile mod if it only stopped my mid range porpoising. Any speed gain at all would be just gravy! The plate on mine is 12" L and about 5 1/4" W on the outside flush edge, which gets tapered inward to fit inside the sea chest. The factory grater was mounted with #8 pan head screws and I used #10 flat head screws, countersunk flush for the new plate. The Lexan can be cut with a sharp carbide tipped table saw blade, and grind corners, edges with a file or sand paper. Kind of like wood, but it heats up and melts when you cut it with a jig saw or hole saw too fast. The holes were drilled a bit crooked at the factory, so they came through the hull beside the sea chest walls. I covered the screws with 4200 inside the bilge to seal them where they came through. I used 4200 around the entire ledge of the sea chest to attach the plate and seal the screw holes. I only used 4200 out of concern for strength, to make sure nothing pops off under pressure. It was hell getting the first edition Lexan grater plate off the boat with 4200 holding it in place. It took a hole saw, cat's paw pry bar, razor blades, caulking remover and patience to get the first prototype plate off. Food for thought. I like the forklift idea, on the rack at the marina! Great idea! I'm with you on the speed gain - just gravy IF you get some, but not the main goal. Quote Link to comment Share on other sites More sharing options...
NCTribute Posted November 29, 2018 Report Share Posted November 29, 2018 This is really interesting. I would think that with the complaints and reputation of porpoising that MBG would be all over this. My biggest dissatisfaction with Pathfinder is the relatively mediocre handling of a premium priced boat. I do realize that there are trade offs for shallow draft, running at speed and rough water, you will likely never satisfy them all and my Pathfinder does do some of the aforementioned operations very well, but the cheese grater feature seems to be the bane of the hull design for a variety of reasons. Hope someone is listening back at the ranch. Quote Link to comment Share on other sites More sharing options...
JEM Posted November 29, 2018 Report Share Posted November 29, 2018 14 hours ago, VsteveV said: I'm heading in the same direction this weekend! Would it be fair to assume the 18 would have the same benefits? And would you need to remove the bunk to get to the plate? Could you just re position the boat on the trailer just to get that work done? Seems to me like you could chain the tongue to a tree, and use a tow strap from your transom to your truck to slide the boat back on the trailer to expose the sea chest. It wouldn't have to be slid very far back to expose it........what, maybe a couple or three feet. When done, just winch it back up tight. Quote Link to comment Share on other sites More sharing options...
JEM Posted November 29, 2018 Report Share Posted November 29, 2018 One other question, Geeviam. Did you drill the angled holes with a hand drill or on a drill press? Quote Link to comment Share on other sites More sharing options...
JEM Posted November 29, 2018 Report Share Posted November 29, 2018 11 hours ago, dabear said: linesider 159 It is almost unheard of to get massive speed gains from a inexpensive bolt on item that can be adjusted or replaced fairly easy so this post has got attention from any speed junky willing to spend a afternoon on his back . Don’t know how many will actually do it but it has a few thinking about it . linesider what was the speed increase that you experienced changing nothing but the cheese grater ? I went back to his thread, and from what I gather, the speed increased from 68.7 to 74.6 just with the cheese grater mod and raising the tabs as far as possible. So really, sounds like they did both changes at the same time, and not really possible to isolate the speed increase due only to the plate. Quote Link to comment Share on other sites More sharing options...
geeviam Posted November 29, 2018 Author Report Share Posted November 29, 2018 38 minutes ago, JEM said: One other question, Geeviam. Did you drill the angled holes with a hand drill or on a drill press? Just a hand drill with my wife as a spotter for the correct angle. I drilled the first hole and then stuck another drill bit in the hole and left it there as a reference so she could guide me on the angles for the other holes, so they would all be the same Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.